Organometallic-compound feeder

ABSTRACT

An organometallic compound feeder comprising a packing container into which an organometallic compound that is in a solid state at an ordinary temperature is to be packed and a carrier gas is to be fed to sublimate the organometallic compound further comprises: 
     a support plate which is to hold the organometallic compound carried on an inert carrier in the packing container and which is to allow the carrier gas to pass therethrough, 
     a carrier gas inlet in an upper portion of the packing container, 
     a carrier gas outlet which is opened below the support plate in a bottom portion of the packing container, and 
     a baffle plate which is attached between the support plate and the carrier gas outlet and is larger than an opening diameter of the carrier gas outlet, and 
     the feeder is configured so as to allow carrier gas to pass downward through the organometallic compound carried on the inert carrier packed on the support plate.

TECHNICAL FIELD

The present invention is related to an organometallic-compound feeder. Specifically, the present invention is related to an organometallic-compound feeder wherein: a carrier gas is supplied to an apparatus containing an organometallic compound which is in a solid state at an ordinary temperature, and preferably at an ordinary temperature and an ordinary pressure to prepare the carrier gas containing the organometallic compound at a more stable concentration and supply the prepared gas to an apparatus which uses the organometallic compound; and the carrier gas is prepared by using the organometallic compound contained in the apparatus at a higher availability, that is, the carrier gas can be prepared with a higher usage rate of the organometallic compound.

BACKGROUND ART

The organometallic compound is used as a material for epitaxial growth of a compound semiconductor. In particular, the organometallic compound is often used in the metalorganic chemical vapor deposition process (MOCVD process) which is excellent in mass productivity and controllability.

For example, trimethylgallium and trymethylaluminum which are organometallic compounds being in a liquid state at an ordinary temperature and trimethylindium which is an organometallic compound being in a solid state at the ordinary temperature are used as a material for a device used in a high-mobility electronic device, a high-intensity light device, a high-capacity optical communication laser, a high-density recording laser and so on. Further, another example wherein the organometallic compound which is in a solid state at the ordinary temperature is the use of biscyclopentadienyl magnesium which is used as a p-type dopant for a gallium nitride when manufacturing a blue light-emitting device.

The organometallic compound is packed in a packing container. The carrier gas is passed through the packing container to contact with the organometallic compound and then the organometallic compound is, as vapor, taken into the carrier gas and entrained by the carrier gas to be discharged from the packing container followed by being fed to a vapor deposition apparatus or the like.

A stainless steel cylindrical container is generally used as such a packing container. The packing containers are known which are characterized by bottom structure of the container and an supplying tube for the carrier gas to improve the thermal efficiency, the controllability of the concentration of the organometallic compound in the carrier gas and the usage rate of the compound and so on. Further, a larger packing container is now being used from the viewpoint of improvement in productivity.

Some of the organometallic compounds which are in liquid state at an ordinary temperature, such as trimethylgallium and trimethylammonium, contact easily with the carrier gas by bubbling the carrier gas in the organometallic compound and then are entrained by the carrier gas to be discharged from the packing container. The organometallic compound which is in a liquid state at the ordinary temperature easily flows in the packing container to the bottom of the packing container, and therefore the organometallic compound is efficiently consumed because the bubbling is made securely even if a remaining amount of the organometallic compound in the packing container is low (see FIG. 1).

On the other hand, in the case where the organometallic compound which is in a solid state at the ordinary temperature, such as trimethylindium, is packed as it is, a portion of the organometallic compound which portion directly contacts with the carrier gas is preferentially consumed, that is, entrained by the carrier gas compared to the other portions of organometallic compound. Once the partial consumption starts, the consumption of the organometallic compound in the portion is facilitated and then a path where the carrier gas easily flows is formed, since the organometallic compound has poor flowability. When such a path is formed, the contact area between the carrier gas and the organometallic compound is reduced and the concentration of the organometallic compound in the carrier gas which is discharged from the packing container is gradually reduced. As a result, the organometallic compound cannot be supplied stably into a reactor such as an MOCVD apparatus.

In general, since the use of the organometallic compound is stopped when the concentration of the organometallic compound in the carrier gas is reduced, the solid organometallic compound which is not consumed is remained in the packing container as shown in FIG. 2. Therefore, when the organometallic compound which is in a solid state at the ordinary temperature is packed as it is, the carrier gas containing the organometallic compound at a stable concentration is not obtained for a long period of time, and the organometallic compound is not used efficiently.

If the usage rate of the solid organometallic compound remained in the packing container is low, the productivity is reduced, which is not preferable. For this reason, various approaches are attempted to supply the carrier gas which contains the solid organometallic compound packed in the container at a constant concentration, and to pass the carrier gas through the solid organometallic compound packed in the container uniformly so that the organometallic compound is used efficiently.

For example, a method using a diffuser (see Patent Document 1), a method disposing a filler on the solid organometallic compound (see Patent Document 2), and a method wherein the carrier gas is introduced in a approximately vertical direction relative to the central axis of the container (see Patent Document 3) are suggested as a method for diffusing the carrier gas at an early stage of the introduction thereof into the container.

Further, there are suggested, as a method for passing the carrier gas through the solid organometallic compound uniformly for efficient contact between the carrier gas and the organometallic compound, a method wherein the solid organometallic compound carried on an inert carrier is packed in the packing container and the carrier gas is flowed downward from above through the packed portion (see FIG. 3) (see Patent Document 4), a method wherein the solid organometallic compound are packed together with a filler (Patent Document 5) and so on. The solid organometallic compound is consumed uniformly at an early stage of the carrier gas introduction by these methods.

On the other hand, there are suggested, as a method for discharging the carrier gas, a method of using a container wherein a tip portion of a carrier gas discharging tube is placed in the solid organometallic compound (see Patent Document 4), a method wherein a porous element is used for an outlet of the carrier gas (see Patent Documents 2 and 6) and so on.

However, there are various problems in methods for discharging the carrier gas. The consumption of the solid organometallic compound proceeds sequentially from an inlet of the carrier gas, which results in problem that the consumption becomes non-uniform due to the distribution of flow rate near the portion where the carrier gas is discharged, as the consumption proceeds,

For example, in the method wherein the carrier gas discharging tube is used, the carrier gas concentrates in the tip portion of the discharging tube which portion is disposed in the bottom of the packing container, and a difference in flow rate of the carrier gas between near a wall of the bottom of the packing container and near the outlet of the carrier gas becomes large. For this reason, the solid organometallic compound is preferentially consumed near the tip of the carrier gas discharging tube than that near the wall of the bottom of the packing container. Thus, when a sufficient amount of the solid organometallic compound does not exist near the tip portion of the carrier gas discharging tube, the concentration of the organometallic compound in the discharged carrier gas is reduced. As a result, the gas which contains the organometallic compound at a desired concentration cannot be supplied stably into the reactor such as the MOCVD apparatus in spite of the fact that the solid organometallic compound is remained in the packing container.

This problem is more noticeable when the amount of the carrier gas introduced into the packing container is increased to conform to the increase in the size of the packing container which is packed with the solid organometallic compound and the increase in the supply amount per unit time of the carrier gas, which results from the increase in consumption amount of the organometallic compound due to the use of a larger reactor such as the MOCVD apparatus. In other words, it is more difficult that the carrier gas containing the organometallic compound at a stable concentration is discharged for a long period of time, while the solid organometallic compound remained in the packing container is efficiently consumed.

There is suggested, as a method to solve the problem found when discharging the carrier gas, a packing container wherein a sintered metal filter or a porous plate is employed is suggested (see Patent Document 7). However, clogging is caused by the solid organometallic compound when the opening size in the sintered metal or the porous plate is small, whereby drift occurs in the carrier gas which passes through the solid organometallic compound. It is considered that this results in a cause of nonuniform consumption of the solid organometallic compound.

[Patent Document 1] JP 02-124796 A

[Patent Document 2] JP 2007-314878 A

[Patent Document 3] JP 2007-225595 A

[Patent Document 4] JP 1-265511 A

[Patent Document 5] JP 5-39915 B

[Patent Document 6] JP 2002-83777 A

[Patent Document 7] JP 2006-161162 A

DISCLOSURE OF INVENTION Problems to be Solved by Invention

The object of the present invention is to provide an organometallic feeder which prepares a carrier gas containing an organometallic compound, in particular the organometallic compound that is in a solid state at an ordinary temperature, at a more stable concentration and feeds the carrier gas to another apparatus (for example, an organometal vapor phase deposition apparatus) and enables the usage rate of the packed solid organometallic compound to be increased.

Means to Solve the Problem

The present inventors intensively studied the feeder for the organometallic compound which is in a solid state at an ordinary temperature, in particular at ordinary temperature and pressure, and have found that the solid organometallic compound is efficiently used when using an organometallic compound feeder comprising:

a packing container which is to receive an organometallic compound carried on an inert carrier,

a support plate which is to hold the organometallic compound in the packing container, particularly in a lower portion of the packing container and which is to allow the carrier gas to pass therethrough,

a carrier gas inlet which is positioned at an upper portion of the packing container,

a carrier gas outlet which is positioned at a bottom portion of the packing container and opened below the support plate, and

a baffle plate which is attached to between the support plate and the carrier gas outlet and is larger than the carrier gas outlet,

wherein the carrier gas is introduced from the carrier gas inlet into the packing container and passes downward from above through the organometallic compound hold on the support plate from, followed by being discharged from the carrier gas outlet, so that the present invention has been completed.

Therefore, the present invention consists in an organometallic compound feeder including a packing container into which an organometallic compound that is in a solid state at an ordinary temperature is to be packed and a carrier gas is to be fed to sublimates the organometallic compound, which feeder further comprises:

a support plate (9) which is to hold the organometallic compound (8) carried on an inert carrier in the packing container (1) and which is to allow the carrier gas to pass therethrough,

a carrier gas inlet (4) in an upper portion of the packing container,

a carrier gas outlet (5) which is opened below the support plate in a bottom portion of the packing container, and

a baffle plate (10) which is attached to between the support plate (9) and the carrier gas outlet (5) and is larger than an opening diameter of the carrier gas outlet (5), and

which is configured so as to allow the carrier gas to pass downward through the organometallic compound carried on the inert carrier packed on the support plate.

Effect of Invention

The use of the feeder of the present invention can supply the organometallic compound which is in a solid state at the ordinary temperature by allowing the compound to be entrained by the carrier gas at a more stable concentration and can increase the usage efficiency of the organometallic compound packed in the packing container.

BRIEF DESCRIPTION OF DRAWINGS

[FIG. 1] FIG. 1 is a schematic cross-sectional view of a packing container which is packed with a liquid organometallic compound.

[FIG. 2] FIG. 2 is a schematic cross-sectional view of a packing container which is packed with a solid organometallic compound.

[FIG. 3] FIG. 3 is a schematic cross-sectional view of a prior art packing container which is packed with the solid organometallic compound carried on an inert carrier.

[FIG. 4] FIG. 4 is a schematic cross-sectional view of an embodiment of an organometallic compound feeder according to the present invention, including a packing container which is packed with a solid organometallic compound carried on an inert carrier.

[FIG. 5] FIG. 5 is a schematic cross-sectional view of another embodiment of an organometallic compound feeder according to the present invention, including a packing container which is packed with a solid organometallic compound carried on an inert carrier.

[FIG. 6] FIG. 6 shows schematic plan views of examples of support plates ((a) a metal mesh-like support plate, (b) a grating-like plate).

[FIG. 7] FIG. 7 is a graph showing results of Example 1.

[FIG. 8] FIG. 8 is a graph showing results of Example 2.

[FIG. 9] FIG. 9 is a graph showing results of Example 3.

[FIG. 10] FIG. 10 is a graph showing results of Comparative Example.

[FIG. 11] FIG. 11 is a graph showing influence of a size of a baffle plate on the effect.

[FIG. 12] FIG. 12 shows schematic cross-sectional views of other embodiments of baffle plates ((a) a conical baffle plate, (b) an inverted conical baffle plate, and (c) a baffle plate comprised of semicircular plates attached at different levels).

EXPLANATION OF REFERENCE NUMERALS

1 Packing container

2 Carrier gas supplying tube

3 Carrier gas discharging tube

4 Carrier gas inlet

5 Carrier gas outlet

6 Liquid organometallic compound

7 Solid organometallic compound

8 Solid organometallic compound carried on inert carrier

9 Support plate

10 Baffle plate

11 Distribution plate

Embodiments for Carrying Out the Invention

The solid organometallic compounds which are packed in the feeder of the present invention are in solid state at an ordinary temperature, in particular at an ordinary temperature and an ordinary pressure and, for example, useful for materials for semiconductor materials produced by the vapor phase deposition method, specifically including the followings: indium compounds such as trimethylindium, dimethylchlorindium, cyclopentadienylindium, trimethylindium/trimethylarsine adduct, trimethylindium/trimethylphosphine adduct and so on; zinc compounds such as zinc ethyliodozinc, ethylcyclopentadienyl zinc, cyclopentadienyl zinc and so on; aluminum compounds such as methyldichloraluminum; gallium compounds such as methyldichlorgallium, dimethylchlorgallium, dimethylbromogallium and so on; and biscyclopentadienyl magnesium.

Further, the carrier for carrying such organometallic compound is not limited to a particular one as long as the carrier is inert to the solid organometallic compound. For example, the followings may be used: ceramics such as alumina, silica, mullite, glassy carbon, graphite, potassium titanate, quartz, silicon nitride, boron nitride, silicon carbide and so on; metals such as stainless steel, aluminum, nickel, tungsten and so on; fluoride resins; and glasses. A shape of the carrier is not limited to a particular one and may be in any shape such as an irregular shape, a sphere shape, a fibrous shape, a mesh shape, a coil shape, a cylindrical shape or the like. It is preferable that the carrier has micro concavities and convexities having a size of from 100 μm to 2000 μm or many pores (or voids) in itself rather than the carrier having a smooth surface. Such carriers include an alumina ball, a Raschig ring, a heli pack, a Dixon packing, a stainless-steel sintered element, glass wool, and metal wool and so on.

As the support plate, a metal mesh-like one and a grating-like one as shown in FIG. 6 are exemplified. The support has a hole in the center portion for the discharging tube. The sufficient opening size of the support plate is such that the carrier does not fall therethrough. Generally, the support plate having the opening size of from about 1 mm to about 5 mm, preferably from about 1.5 mm to about 3 mm is used. The shape of the opening is not limited to a particular one and, for example, a polygonal shape, a circular shape, and an elliptical shape are exemplified as the shape of the opening. The material for the support plate is not limited to a particular one as long as it is inert to the solid organometallic compound. For example, a glass, a metal or a ceramic or the like may be used. The metal is preferable from the viewpoint of thermal conductivity and the support plate of stainless steel is particularly preferable.

On the other hand, a sintered metal filter may be used as the support plate. However, when the opening of the sintered metal is too fine, there is possibility of a large pressure loss or clogging, resulting in the drift of the carrier gas.

In the organometallic compound feeder according to the present invention, the carrier gas inlet and the carrier gas outlet means an entry of the carrier gas into the packing container and an exit of the carrier gas from the packing container, respectively. In one preferable embodiment, the carrier gas inlet and the carrier gas outlet are an opening at end of a pipe as a supplying tube supplying the carrier gas into the packing container and an opening at end of a pipe as a discharging tube discharging the carrier gas from the packing container, respectively. In general, such gas pipes are tubes having a circular cross section. In this case, the shapes of the inlet and the outlet are also circular. Of course, the inlet and the outlet may have another shape and the pipe through which the carrier gas correspondingly has the another cross-sectional shape. In another embodiment, the inlet and the outlet may be openings provided directly in the packing container.

In the organometallic feeder of the present invention, the baffle plate is a plate positioned between the support plate and the carrier gas outlet. As a result, the entire flow of the carrier gas which falls through a region of the organometallic compound which region is positioned just above the baffle plate (a substantially vertical and downward-direction flow or the flow of which direction is similar to that direction) impinges against or inclines to impinge against the baffle plate and thereby the flow direction of the carrier gas is changed into another direction by the baffle plate. For example, the carrier gas flows in a direction which is not vertical and downward. More specifically, it flows in a direction toward a side wall of the packing container (for example, a horizontal direction or an obliquely downward direction). After that, such carrier gas is turn around the baffle plate and flow toward the carrier gas outlet positioned beneath the baffle plate.

It is effective that the outlet is made large by increasing a diameter of the pipe through which the carrier gas flows in order to prevent the flow rate of the carrier gas from being increased due to the concentration of the carrier gas near the carrier gas outlet. It should be noted that the packed solid organometallic compound may pass through the pipe to be discharged from the packing container remaining in a solid form when the carrier gas is passed at a large flow rate. Considering this, it is preferable that the carrier gas outlet is optimally small, without being too large. In general, a pipe with an outer diameter of 10 mm is used as the carrier gas discharging tube. Attachment of the baffle plate with a larger size than the pipe diameter allows the carrier gas to turn around the baffle plate followed by being discharged from the packing container. This allows more carrier gas to flow near the side wall of the packing container and thereby the carrier gas is prevented from directly concentrating in the tip portion of the carrier gas discharging tube without passing near the side wall of the packing container.

In the present description, the shape and the size of the baffle plate mean a shape and a size of a region which are obtained by normally projecting a structure which is constructed below the support plate as the baffle plate, on a plane which is perpendicular to a longitudinal direction of a barrel of the packing container (therefore, a vertical direction). The baffle plate has the shape and the size such that, when the normal projection of the baffle plate is overlapped with the normal projection of the carrier gas outlet, the normal projection of the baffle plate covers the entire of the normal projection of the outlet and has a portion which extends outward from an periphery of the normal projection of the carrier gas outlet. In the present invention, the expression “the baffle plate which is larger than the opening diameter of the carrier gas outlet” is used in this meaning. It should be noted the effect of the baffle plate is generally obtained when a diagram (or a figure) obtained by normally projecting the baffle plate in a direction which is perpendicular to a longitudinal direction (or an upward and downward direction) of a packing container barrel covers the diagram obtained by normally projecting the outlet similarly and extends outward from the diagram of the outlet. Therefore, the baffle plate is not necessarily required to extend in a vertical direction to the longitudinal direction of the packing container barrel and on the same plane, and it may be oblique relative to the longitudinal direction or may be attached at different levels as shown in FIG. 12.

It should be noted that, even in an embodiment wherein the baffle plate is attached around the carrier gas discharging tube (that is, an embodiment wherein the discharging tube penetrates the baffle plate), the baffle plate can suppress the direct concentration of the carrier gas which does not pass near the side wall of the packing container, into the tip portion of the carrier gas discharging tube. In this embodiment, the shape and the size of the baffle plate means the shape and the size of the baffle plate assuming that the discharging tube does not exist (that is, the discharging tube does not penetrate the baffle plate).

If the size of the baffle plate is too large and become close to the diameter of the packing container barrel, the carrier gas concentrates near the side wall in the bottom portion of the packing container, and thereby it is difficult for the carrier gas to flow around the carrier gas discharging tube which is above the baffle plate, which leads to difficulty in consumption of the solid organometallic compound positioned above the baffle plate. For this reason, it is recommended to use the baffle plate having the diameter of about 10% to about 75% relative to the inner diameter of the packing container, and preferably about 20% to about 60%. It should be noted that the diameter of the baffle plate and the inner diameter of the packing container are based on hydraulic diameters when the cross-sectional shapes of the baffle plates and the packing container are not circular.

The material for the baffle is not limited to a particular one long as it is inert to the solid organometallic compound, and a glass, a metal or a ceramic or the like may be used. The baffle plate of metal is preferable from the viewpoint of the thermal conductivity, and the baffle plate of stainless steel is particularly preferable. The shape of the baffle plate is not limited to a particular one, and a polygonal shape, a circular shape and an elliptical shape are exemplified. From the viewpoint of symmetry, the circular shape is particularly preferable.

The baffle plate is preferably placed away from the solid organometallic compound, rather than in the solid organometallic compound. This is because the consumption of the solid organometallic compound is difficult to occur since the flow of the carrier gas inclines to be interrupted just above the baffle plate when the position of the baffle plate is above the support plate or at the same level as that of the support plate. On the other hand, when the position of the baffle plate is below the support plate, the region where the solid organometallic compound is difficult to be consumed can be small since the solid organometallic compound does not exist in the region just above the baffle plate where the flow of the carrier gas inclines to be interrupted.

Further, it is preferable that the baffle plate, the carrier gas outlet and the circular cross section of the packing container in a horizontal direction at height (or level) where the baffle plate is attached are approximately concentric, that is, the centers of them are positioned in substantially the same vertical line. If they are not concentric, the effect can be obtained to some extent, but the concentric arrangement can increase the usage rate of the solid organometallic compound since the concentric arrangement allows the carrier gas to flow symmetrically, resulting in uniform consumption of the solid organometallic compound.

A method for allowing the inert carrier to carry the solid organometallic compound may be any method which has been conventionally performed. For example, a method wherein the carrier and the solid organometallic compound are charged into a rotatable container at a predetermined weight ratio and then the container is heated to melt the solid organometallic compound followed by gradual cooling the container while rotationally agitating the carrier and the organometallic compound, or a method wherein the carrier is put into the heated and molten solid organometallic compound and excess molten organometallic compound is subsequently removed followed by gradual cooling, may be employed.

It is important to previously remove oxygen, moisture and other volatile impurities contained in the carrier upon the carrying operation. If oxygen and moisture and so on exist on the surface of the carrier, the material solid is transformed or contaminated, which not only deteriorates the quality of the resultant film when the compound is used as the material for the vapor phase deposition, but also precludes the stable material feed which is the intended purpose. In order to avoid such inconvenience, it is recommended that the carrier is previously subjected to a vacuum degassing and heated at a temperature within a range acceptable to the material and then the voids are placed with an inert gas such as nitrogen, argon or the like.

The amount of the solid organometallic compound which is carried on the carrier is from about 10 parts to about 100 parts by weight, preferably about 30 to about 70 parts by weight relative to 100 parts by weight of the carrier. If 10 parts by weight or less of the organometallic compound are carried on the carrier, the packing container should be unnecessarily large because the amount of the solid organometallic compound occupying the volume of the packing container is small, which may be often uneconomical. Further, if 100 parts by weight or more of the organometallic compound are carried on the carrier, sufficient effect cannot be obtained in many cases because a surface area of the solid organometallic compound per packed volume of the container may not be as large as expected.

An embodiment of the organometallic compound feeder of the present invention, which is comprised of a packing container 1 packed with the solid organometallic compound is shown in FIG. 4. A support plate 9 which holds an organometallic compound 8 carried on an inert carrier and allows the carrier gas to pass therethrough is disposed in the lower portion of the packing container 1 having a curved bottom portion. A carrier gas supplying tube 2 and a carrier gas discharging tube 3 are connected to an upper portion of the packing container. A carrier gas inlet 4 opens at the upper portion of the packing container 1 and above the organometallic compound 8 carried on the carrier which is packed in the packing container. The carrier gas discharging 3 passes inside the packing container 1 and a carrier gas outlet 5 opens at the bottom portion of the packing container 1 and below the support plate 9.

In the illustrated embodiment, a baffle plate 10 is attached above the carrier gas outlet 5. In the case where the baffle plate 10 is positioned at the same level as that of the carrier gas outlet 5 (relative to a vertical direction of the packing container 1), the baffle plate 10 makes it possible to change the flow direction of the carrier gas which falls toward the baffle plate so that the carrier gas turns around the baffle plate. Therefore, those skilled in the art will easily understand that the above-described effect of the present invention can be given even in such a case. Therefore, the baffle plate and the carrier gas outlet are plated at substantially the same level and the expression “between the support plate and the carrier gas outlet” includes both of an embodiment wherein the baffle plate is positioned at a level higher than that of the carrier gas outlet and an embodiment wherein the baffle plate is positioned at the same level as that of the carrier gas outlet. It should be noted that, in the embodiment shown in FIG. 4, the baffle plate has a form which extends from the outer wall of the carrier gas discharging tube to the side wall of the packing container (for example, a ring (or a donut) shape which is obtained by removing, from a disc, a central portion which corresponds to the outer shape of the carrier discharging tube).

In the illustrated embodiment, the carrier gas discharging tube 3 passes through the inside of the packing container 1, but the present invention is not limited to this embodiment. The carrier gas discharging tube may be disposed outside the packing container 1 as long as the outlet 5 opens at the bottom portion of the packing container 1 and below the support plate 9.

Further, another embodiment of the organometallic compound feeder of the present invention is shown in FIG. 5, which is comprised of a packing container which is packed with the solid organometallic compound.

The support plate 9 which holds the organometallic compound 8 carried on the inert carrier is positioned in the lower portion of the packing container 1 having a curved bottom portion. The carrier gas supplying tube 2 is connected to the upper portion of the packing container 1. The carrier gas inlet 4 opens at the upper portion of the packing container 1 and above the organometallic compound 8 carried on the carrier which is packed in the container. The carrier gas discharging tube 3 is placed outside the packing container 1 and the carrier gas outlet 5 opens at the bottom portion of the packing container 1 and below the support plate 9. The baffle plate 10 is attached above the carrier gas outlet 5.

In the embodiment shown in FIG. 5, the carrier gas discharging tube 3 is positioned outside the packing container 1. The present invention is not limited to this embodiment and the carrier gas discharging tube may be positioned inside the packing container 1 as long as the outlet opens at the bottom portion of the packing container and below the support plate.

The solid organometallic compound 8 carried on the inert carrier is packed on the plate 9 by supplying a predetermined amount of the compound from the supplying port (not shown) into the packing container 1. The operation of allowing the inert carrier to carry the solid organometallic compound may be made inside the packing container 1 as described above.

The carrier gas supplying tube 2 is connected to a carrier gas source and a flow-rate regulating apparatus (not shown) and so on and the carrier gas discharging tube 3 is connected to a gas concentration meter and a vapor phase deposition apparatus (not shown) and so on. The feeder is used disposing the packing container 1 within, for example, a constant-temperature bath.

The carrier gas such as hydrogen is supplied, at a predetermined flow rate, from the carrier gas supplying tube 2 to the packing container 1. The carrier gas is allowed to advance, via the carrier gas inlet 4, from the upper side to the lower side of the packing container 1 passing through gaps between the organometallic compounds 8 carried on the inert carrier, whereby the carrier gas containing the organometallic compound is supplied from the carrier gas outlet 5 to the vapor phase deposition apparatus via the carrier gas discharging tube 3.

Although each of FIGS. 4 and 5 shows the packing container 1 having a round bottom portion, the packing container having a flat bottom portion can be of course used. Further, the packed amount of the organometallic compound 8 carried on the inert carrier in the packing container 1 (for example, the packing height, that is, the level in the vertical direction of the packing container) is generally selected so that the compound is positioned below the carrier gas inlet 4. However, this is not the case when a construction is employed wherein the carrier gas inlet 4 is divided and the carrier gas can be introduced uniformly in the upper potion of the organometallic compound 8. For example, when the carrier gas can be uniformly decentrally-supplied as in the case where a distribution plate or a shower head-like carrier gas inlet is employed, the level of the carrier gas inlet 4 and the top level of the packed organometallic compound 8 may be approximately the same.

The organometallic compound feeder according to the present invention is suitable as an apparatus for supplying a material for the vapor phase deposition.

Examples of the present invention is described below, but the present invention is not limited thereto.

EXAMPLE 1

An organometallic compound feeder of the present invention was constructed which was similar to that shown in FIG. 4 except that a baffle plate was attached to a tip portion of a discharging tube, that is, a level of an outlet. A bottom portion of a packing container 1 was curved and the packing container 1 had a volume of about 1300 cm³ (an inner diameter: 108 mm, a height: 147 mm). A support plate 9 (a size of opening: 2 mm metal mesh) was placed at 26 mm from a bottommost position of the packing container. A distribution plate 11 (a disc-shaped flat plate: a diameter of 18 mm) was attached at the carrier gas inlet 4 in parallel to a top plate of the packing container 1 so that a distance between the top plate of the packing container and the distribution plate 11 was 3 mm, whereby the carrier gas was introduced in a direction almost vertical relative to the central axis of the container. Further, a carrier gas discharging tube 3 (an outer diameter 8 mm, an inner diameter 6 mm) which opens at 10 mm below the support plate 9 is equipped with, at a tip portion thereof (a carrier gas outlet 5), a baffle plate 10 (a disc-shaped flat plate of a diameter of 30 mm, wherein the discharging tube passes in the center portion).

The packing container 1 was packed with 585 g alumina spheres having a mean particle size (a diameter) of 4.5 mm

as an inter carrier and 300 g trimethylindium (referred to as TMI hereinafter). The packed packing container 1 was heated to about 110° C. to melt TMI in the packing container and cooled gradually to a room temperature under rotational agitation so as to allow the alumina carrier to carry TMI.

A hydrogen gas as the carrier gas was supplied from the carrier gas supplying tube 2 into this packing container 1 so that the gas advanced downward from above through the packed TMI at an approximately constant rate of about 900 cm³ (a converted value at an atmospheric pressure, a flow rate per unit area of the packed portion: about 9.5 cm³/cm²·min), and then the hydrogen gas containing TMI was discharged via the carrier gas outlet 5 from the carrier gas discharging tube 3. The leading of TMI from the packing container 1 with the hydrogen gas as the carrier gas was conducted while a pressure inside the packing container 1 was made 40 kPa (an absolute pressure) and a temperature of the packing container 1 was kept at 25° C. by putting the packing container 1 into a constant-temperature bath.

A concentration of TMI in the hydrogen gas from the packing container 1 was determined by an EPISON analyzer (made by Thomas Swan Scientific Equipment Ltd.) as a gas concentration meter. The TMI concentration was determined periodically and the usage rate (%) of TMI was calculated from the hydrogen gas flow rate and the TMI concentration. The results are shown in FIG. 7. The TMI concentration was kept stable until the usage rate reached about 87%, and then reduced.

EXAMPLE 2

The alumina spheres were allowed to carry TMI thereon in the same packing container 1 as that used in Example 1, in the same manner as that in Example 1 except that the diameter of the baffle plate 10 (the disc-shaped flat plate) which was attached to the tip portion of the carrier gas discharging tube 3 (the carrier gas outlet 5) was 50 mm.

The usage rate of TMI was determined in the same manner as that in Example 1. The results are shown in FIG. 8. The TMI concentration was kept stable until the usage rate reached about 87%, and then reduced.

EXAMPLE 3

The alumina spheres were allowed to carry TMI thereon in the same packing container 1 as that used in Example 1, in the same manner as that in Example 1 except that the diameter of the baffle plate 10 (the disc-shaped flat plate) which was attached to the tip portion of the carrier gas discharging tube 3 (the carrier gas outlet 5) was 80 mm.

The usage rate of TMI was determined in the same manner as that in Example 1. The results are shown in FIG. 9. The TMI concentration was kept stable until the usage ratio reached about 85%, and then reduced.

COMPARATIVE EXAMPLE 1

The alumina spheres were allowed to carry TMI thereon in the same packing container 1 as that used in Example 1, in the same manner as that in Example 1 except that the baffle plate 10 (the disc-shaped flat plate) was not attached to the tip portion of the carrier gas discharging tube 3.

The usage rate of TMI was determined in the same manner as that in Example 1. The results are shown in FIG. 10. The TMI concentration was stable until the usage rate reached about 83%, and then reduced. The relationship between the usage rate of TMI and the ratio of the baffle plate size to the inner diameter of the packing container is shown in FIG. 11. 

1. An organometallic compound feeder comprising a packing container into which an organometallic compound that is in a solid state at an ordinary temperature is to be packed and a carrier gas is to be fed to sublimate the organometallic compound, which feeder further comprises: a support plate which is to hold the organometallic compound carried on an inert carrier in the packing container and which is to allow the carrier gas to pass therethrough, a carrier gas inlet in an upper portion of the packing container, a carrier gas outlet which is opened below the support plate, in a bottom portion of the packing container, and a baffle plate which is attached to between the support plate and the carrier gas outlet and is larger than an opening diameter of the carrier gas outlet, and which is configured so as to allow the carrier gas to pass downward through the organometallic compound carried on the inert carrier packed on the support plate.
 2. The organometallic compound feeder according to claim 1, wherein the support plate is a metal mesh of stainless steel having an opening size of from 1 mm to 5 mm.
 3. The organometallic compound feeder according to claim 1 or 2, wherein the baffle plate which is larger than the opening diameter of the carrier gas outlet is a disc-shaped flat plate and is placed approximately concentrically with the support plate and a barrel of the packing container.
 4. The organometallic compound feeder according to claim 1, wherein the carrier gas inlet is constructed such that the carrier gas supplied from the carrier gas inlet is ejected in a direction which is approximately perpendicular to a central axis of the packing container when the container is installed vertically.
 5. The organometallic compound feeder according to claim 1, wherein the organometallic compound is trimethylindium. 